Gas Sensor Controller Deterioration Detection via Voltage Shift
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Solution Overview
Problem
Gas sensors, such as NOx sensors, face a challenge in determining the deterioration state of their elements, which can lead to slow response times and failure to meet regulatory requirements due to aging or other causes, necessitating a method to assess and manage sensor deterioration.
Innovation Solution
A gas sensor controller system with a first and second measurement chamber, featuring a first pump cell, a second pump cell, and an oxygen concentration detection cell, allows for the determination of sensor deterioration by changing the target voltage and analyzing the resulting concentration current, using indices like response time to assess the degree of deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the gas sensor element is used for a long time, then the sensor can continuously monitor gas concentration, but the response of the sensor becomes slow
Solution Approach 1:
The system performs preliminary deterioration assessment by introducing a predetermined concentration of oxygen-containing gas and measuring the concentration current before actual use. This allows the controller to predict future response performance and schedule maintenance before the sensor actually deteriorates to unacceptable levels, resolving the contradiction between extended service life and maintained response speed.
Solution Approach 2:
The gas sensor controller continuously monitors the concentration current and compares it against reference values to provide feedback on sensor deterioration. This feedback mechanism enables the system to track performance degradation over time and trigger maintenance actions when response speed falls below thresholds, balancing continuous operation with performance maintenance.
2Measurement precision
If the target voltage is changed to determine deterioration state, then the deterioration state can be assessed, but the measurement process becomes more complex
Solution Approach 1:
The system determines deterioration state by changing the target voltage from a first value to a second value and measuring the concentration current response. This parameter change approach provides multiple data points for accurate deterioration assessment while the controller manages the complexity through automated voltage sequencing and current measurement protocols.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively determines the deterioration state of gas sensor elements by analyzing changes in concentration current, enabling timely replacement and maintaining compliance with response time requirements, thus ensuring accurate gas concentration measurements.
Implementation Method 1
a first pump cell which is formed of a first solid electrolyte body and which pumps oxygen out of the first chamber gas within the first measurement chamber or pumps oxygen into the first measurement chamber
Implementation Method 2
When a predetermined voltage is applied to the second pump cell, oxygen molecules and oxygen-containing gas molecules including oxygen atoms in their respective structures (e.g., NOx) introduced into the second measurement chamber from the first measurement chamber are disassociated. As a result, a concentration current corresponding to the concentration of the oxygen molecules and oxygen-containing gas molecules contained in the second chamber gas flows between the electrodes of the second pump cell.
Implementation Method 3
a concentration current corresponding to the concentration of the oxygen molecules and oxygen-containing gas molecules contained in the second chamber gas flows between the electrodes of the second pump cell
Implementation Method 4
an oxygen concentration detection cell which is formed of a third solid electrolyte body and which has detection and reference electrodes formed on the third solid electrolyte body such that the detection electrode is located in the first measurement chamber and the reference electrode is exposed to an atmosphere having a reference oxygen concentration
Data Source
AI summary
A gas sensor controller (100) controls a gas sensor element (10) which has a first pump cell (111), a second pump cell (113), and an oxygen concentration detection cell (112). The controller includes first chamber control means (51) to (53) which pumps oxygen out of or into a first measurement chamber MR1 such that a concentration voltage Vs becomes equal to a target voltage Vr; target voltage changing means S72, S75 which changes the target voltage Vr from a first target voltage Vr1 to a second target voltage Vr2; current detection means (55) which detects the magnitude of a concentration current Ip2 flowing between first electrode (145) and second electrode (147); and deterioration determination means S7 which determines the deterioration state of the gas sensor element from a change which occurs in the concentration current Ip2 due to the change in the target voltage Vr.